By Bob Tedeschi

Published: January 14, 2002

FOR Internet retailers, the teenage market is much like the China market. Both are huge and largely inaccessible because the targets speak completely different languages than most mainstream American merchants.

E-tailers simply cannot ignore the under-18 population, since this group spends roughly $155 billion a year in the United States, according to Teen Research Unlimited, a consulting firm. And 80 percent of those teenagers are online already. But they spend a paltry $1 billion of their cash online, according to Jupiter Media, an Internet research firm, a level that speaks to the inability of online merchants to entice teenagers to do more than download free music, play games and ping each other with instant messages.

But analysts have long said that the e-tailers are not solely to blame. Because the preferred currency of the Web -- the credit card -- remains out of reach for many teenagers and preteenagers, young people often have to ask their parents for the plastic if they want to buy something online. Adding this layer of parental screening to the purchase process is enough to send teenagers straight to the mall, where their friends are their only shopping companions.

That is not to say that the three major credit card companies have not tried to penetrate the teenage market with products meant to start young consumers' spending online. MasterCard International is reportedly testing a teenage-oriented card, although Mastercard will not talk about such a project. Visa USA rolled out its Visa Buxx card in 2000, to mixed results.

And American Express killed its year-old Cobaltcard effort in November, after its dot-com partner, the Zowi Corporation, suspended operations. But analysts said Cobaltcard, which was aimed squarely at the youth market, was dying a slow death anyway, with too few teenagers interested for the companies to justify the higher-than-expected cost of keeping it alive.

''The idea of a teen card is a good one,'' said Aaron McPherson, an analyst with IDC, a consulting firm. ''The card companies just haven't found the right formula, yet.''

The three main components of that formula, Mr. McPherson and other said, include the fees associated with the cards, how they are marketed and the ways teenagers can use them. Companies seem to agree that the cards should simply be so-called stored value devices, or debit cards, allowing parents or others to put cash value into the card account through an advance from the parent's credit card account or some other means.

Since the teenage users are not taking on debt with such cards, the approach has enabled card companies to deflect critics who accuse them of cultivating a population of future debt addicts.

Pricing has been a trickier proposition. Because the credit card companies do not charge interest for these cards, the companies must instead charge use fees. The Capital One Visa Buxx card, for instance, charges $2 a month to put money into the account, and $1 each time a customer checks the account balance at an A.T.M.

According to Zack Martin, associate editor of Thomson Financial's Card Marketing magazine, an industry publication, many teenagers ''get the card thinking it's a good idea, but they realize they're getting nickel-and-dimed on fees, so they don't use them anymore.''

Another big drawback, analysts said, is that the credit card companies have been unable to figure out how to market the cards in a way that will appeal to both parents and teenagers. Mr. Martin, of Card Marketing, said: ''Some people say you need to advertise it to the teens, with ads that are so obnoxious parents wouldn't want them to have it. That way the teen will want it more.''

Visa said that it had not yet planned its marketing approach for 2002, but that the organization was pleased with the progress of Visa Buxx. Rhonda Bentz, a Visa spokeswoman, would not disclose use or profitability figures, but said that six Visa card issuers now offered Visa Buxx, ''and many more are looking at it this year.''

Ms. Bentz said she was not sure whether the Visa Buxx program had induced more teenagers to shop online. Internet merchants are uncertain, too, because the card numbers do not distinguish between Visa Buxx accounts and typical Visa accounts. But some e-tailers are hopeful the debit-card programs will eventually make a difference in sales, even if they suspect the programs are not doing much now.

Consider Bertelsmann's CDNow music Web site. According to Sharon Siegel, who is senior vice president for marketing for CDNow and BMG Music Service, about a third of CDNow's visitors are from 12 to 24, ''so a big chunk are teens.'' And yet, only about 3 percent of the site's paying customers are teenagers.

The dearth of credit cards available to teenagers ''is clearly an obstacle'' to their spending more on the site, Ms. Siegel said. That is why CDNow is likely to promote the Visa Buxx product after Bertelsmann finishes integrating CDNow's operations with those of the BMG Music Service.

Mr. McPherson, the IDC analyst, said teenagers would warm to the idea of online debit cards much more quickly if more companies followed the lead of Coca-Cola's RocketCash, which has developed an online scrip for teenagers. About 2.3 million young people have deposited cash into their RocketCash accounts, which function like debit cards at scores of online merchants.

Mr. McPherson was even more enthusiastic about the company's customer loyalty promotions, like the one RocketCash has conducted with Sprite since late 2000. In that effort, Sprite customers find RocketCash codes beneath their bottle tops. The codes are redeemable for RocketCash, which itself can be redeemed for merchandise at several online stores, like Magazines.com.

''We see loyalty programs like this as a way to prime the pump, and get more teens to try it out,'' Mr. McPherson said. If big brands are involved, marketing might be more effective.

Still, even if Visa, American Express and MasterCard were to put a card in the hands of every teenage Internet user, analysts said it might not increase their online spending, since teenagers may still prefer the mall in most instances. Meanwhile, the few online categories that are aimed specifically at young shoppers seem to manage without the widespread use of teenage debit cards.

One example is Delia's, which sells apparel and accessories to teenage girls through catalogs, stores and a Web site (www.delias.com). Delia's has more than three million customers who shop online, with more than half of them buyers, according to Evan Guillemin, the company's chief operating officer.

Mr. Guillemin estimated that 1 percent or less of the company's online customers use debit cards, while 5 percent to 10 percent pay by check. The rest, he said, use their parents' credit cards.

''If you can deliver the right merchandise in a way that's compelling for the kid, and establish their trust, they'll find a way to buy it from you,'' he said. ''Most kids have access to a credit card, one way or another.''

Photo: Thomas Madden, seated, of Saco, Me., surveys the RocketCash Web site with his parents, Debbie and Edward. RocketCash has developed online debit accounts for young people. (Herb Swanson for The New York Times)